A redox flow battery (“RFB”) system is a form of rechargeable battery/fuel cell in which an electrolyte containing one or more dissolved electroactive species flows through an electrochemical cell that converts chemical energy to electricity. The electrolyte is stored externally, generally in tanks, and is circulated through the cell (or cells) of the battery system. Control of flow batteries requires knowledge of a flow rate and a State of Charge (“SOC”) of the cell. Together these two factors determine the concentration and availability of reactants at the electrodes, and the current that can be drawn from the cell for the best efficiency within predetermined operating limits. The SOC is also used to determine how much energy the battery is capable of storing or delivering. The identified SOC may also determine the power that the battery is capable of producing at any given time during the discharge process.
One particular type of redox flow battery system is referred to as an H2/Br2 battery system. This type of battery system provides high-quality electricity under safe and economic conditions. Other characteristics of H2/Br2 battery systems include a high-intrinsic reversibility of the electrode reactions, high-power capabilities, and extended cycle life. As a result of the above-described benefits and characteristics, H2/Br2 battery systems show potential as a viable battery system for grid-scale energy storage.
One concern of H2/Br2 battery systems is that halide species present in the battery system could “poison” electrocatalytic surfaces of the electrode(s) (typically the anode electrode), thereby compromising the cell life. Despite collected evidence for the poisoning effect of halides on various catalytic surfaces in other types of battery systems, a systematic study that has determined the effects of halide poisoning in the H2/Br2 battery system is unavailable. It is likely that evidence of the poisoning effects is unavailable due to the complexity of measuring the adsorption of bromine species on platinum-like metals. Accordingly, the concern of electrocatalytic surface poisoning in H2/Br2 battery systems is a potential limitation that should be addressed.
In light of the foregoing limitations in the art, a need exists for an improved H2/Br2 battery system that is less susceptible to poisoning of the anode electrode.